Placeholders are used in detail messages to provide relevant details such as the value the user entered and the label of the component for which this is a message. The general order of placeholder identifiers is:

{0} The label that identifies the component
{1} Value entered by the user
{2} Example of the format the converter is expecting

B.3.3 af:convertNumber

Provides an extension of the standard JSF javax.faces.convert.NumberConverter class. The converter provides all the standard functionality of the default NumberConverter and is strict while converting to an object.

Convert number: Input value cannot be converted to a Number, based on the pattern set